The present invention relates to passenger aircraft and more specifically to passenger aircraft with wing tip devices, and to methods of operating such aircraft.
There is a trend towards increasingly large passenger aircraft, for which it is desirable to have correspondingly large wing spans. However, the maximum aircraft span is effectively limited by airport operating rules which govern various clearances required when manoeuvring around the airport (such as the span and/or ground clearance required for gate entry and safe taxiway usage).
In some suggested designs, aircraft are provided with wings which may be folded upwardly to reduce the span of the aircraft on the ground (compared to when the aircraft is configured for flight). However, a disadvantage with such arrangements is that they tend to require heavy actuators and/or locking mechanisms to deploy the wing and to securely hold it in the flight configuration.
Another disadvantage in upwardly folding wings is that the aerodynamic lift forces on the wing during use, tend to be urging the wing towards the folded position. Thus, in the theoretical event of an equipment failure (for example an actuator or lock failure) the wing may be liable to fold upwards. Even if safety systems are in place to prevent this, there may at least be an adverse passenger perception of such a possibility occurring.
The present invention seeks to mitigate at least some of the above-mentioned problems.